The present invention relates to an optical disk permitting reading and writing of data while being rotated at a constant angular velocity, and more particularly to an optical disk having a recording surface divided into a plurality of zones, with clocks of higher frequencies being used for the access to the more outward zones so that the recording linear density is substantially identical between the outer and inner zones.
The present invention also relates to an optical disk which contains different types of recording media for the respective zones, and in which the types of the respective zones can be altered during use of the disk.
The present invention also relates to an optical disk drive device used for writing in and reading from the above-mentioned optical disks.
Known optical disks of the type having a storage capacity of 1 GB on each surface have a format proposed in ECMA/TC31/92/36. According to this proposal, the recording surface of the optical disk is divided into a plurality of zones equally, i.e., such that the numbers of the physical tracks in the respective zones are substantialy equal. The number of zones depends on the size of the sector. If each sector consists of 512 bytes, the number of the zones is 54. If each sector consists of 1024 bytes, the number of the zones is 30.
Each physical track has an integer number of sectors The number of sectors in each track is constant throughout each zone. The number of sectors in each track is larger in more outward zones.
The optical disks that are available are either those of the R/W (read/write or rewritable) type which permit writing and rewriting as desired, and those of the WO (write-once) type which permit writing only once after fabrication, and those of O-ROM (embossed) type in which data is written at the time of fabrication, by embossing, and which do not permit writing after fabrication.
The number of sectors in each physical track differs from one zone to another, as described above. A complex algorithm is needed for indexing the physical location of the target sector when for instance the optical disk is used as a SCSI device, and is supplied with linear (consecutive-integer-numbered) logical addresses. Moreover, the data field in each sector in an innermost physical track of a certain zone and the header field in each sector in an outermost physical track of another zone next to and inside of the first-mentioned zone may be adjacent to catch other, with the result that the crosstalk from the header field may degrade the quality of the data read from the data field. This is because the information in the header field is written in the form of pit (embossment) and has a greater degree of modulation, causing a greater crosstalk, while the information in the data field is magneto-optically written and has a smaller degree of modulation. In this connection, it is noted that within each zone, header fields in all the tracks are radially aligned and data fields in all the tracks are radially aligned, so that a header field and a data field will not be adjacent to each other.
It is also desired that recording areas of the R/W type, of the WO type and of the O-ROM type be co-existing in a single disk to expand the application of the disks. In the past, optical disks of the P-ROM type, in which the recording areas of the R/W type and the recording areas of the O-ROM type are coexisting, were available. But, no other combination of recording areas have been known.
An object of the invention is to provide an optical disk which enables quick indexing of the physical location of the target sector responsive to a given address.
Another object of the invention is to provide an optical disk permitting mixed presence of recording areas of different types.
A further object of the invention is to provide an optical disk drive used for such optical disks.
According to a first aspect of the invention, there is provided an optical disk comprising a recording region, physical tracks in said recording region each corresponding to one revolution, said recording region being divided into a plurality of zones by one or more circular boundary lines centered on the center of the disk, each zone comprising a plurality of physical tracks adjacent to each other, wherein an integer number of sectors are provided in each physical track, the angular recording density is higher in the more outward zones such that the linear recording density is substantially constant throughout the recording region, and logical tracks are formed of a predetermined number of sectors, independent of the physical tracks.
With the above arrangement, each logical track is formed of sectors, independent of the physical tracks, and the number of the sectors in each logical track is constant throughout the recording region, regardless of the radial position of the sector within the recording region, so that the conversion between the logical track and sector addresses read from the disk, at the sectors being accessed by the read/write head, and the linear logical addresses (one-dimensional addresses, or addresses represented by consecutive integers) supplied from a host device is easy, and the grouping and defect management are easy.
The addresses written in headers of the sectors in the logical track in which data are actually recorded,including substitute sectors used in place of defect sectors, are preferably consecutive to further facilitate the conversion between the logical track and sector addresses read from the disk and the linear logical addresses supplied from the host device.
The difference obtained by subtracting the number of the logical tracks corresponding to each zone from the number of the logical tracks corresponding to another zone adjacent to and radially outside of said each zone is preferably constant.
With this arrangement, the address management of the disk is facilitated, and the number of the logical tracks in the zone in question can be determined through simple calculation on integers, without referring to a table for address conversion, and the determination of the target sector during seek operation can be made with ease.
The number of the physical tracks of zones adjacent to each other are preferably made equal by providing sectors in which data is not recorded.
With this arrangement, the calculation for determining the number of tracks to be traversed for accessing the target track is easy, and the management of the physical location is easy.
Addresses of the sectors in the tracks in which data is not recorded may be assigned independently of the addresses of the sectors in the tracks in which data is recorded. Similarly, addresses of the sectors in the test track in each zone are assigned independently of the addresses of the sectors in the tracks in which data is recorded. With this arrangement, management of the tracks in which data is not recorded and the test tracks is facilitated. The logical track and sector addresses are of consecutive values, so that the address management of the recorded data is facilitated. Access management of the test tracks is also facilitated.
The difference obtained by subtracting the number of sectors in each zone in which data is not recorded from the number of sectors in another zone adjacent to and outside of said each zone and in which data is not recorded is preferably constant.
With this arrangement, the number of the sectors in each zone in which data is not recorded can be determined through simple calculation on integers, without referring to a table, and the address management of the disk is easy.
Data may not be recorded in the outermost and innermost physical tracks in each zone. This arrangement avoids crosstalk at the boundary between zones. That is the header fields are not necessary aligned radially between different zones, and the header fields and the data fields of tracks adjacent to each other and belonging to different zones may be adjacent to each other. However, by the above arrangement in which the outermost and innermost physical tracks are not used for recording data, the tracks in which data is recorded is separated from the tracks of a different zone, by at least one track in the same zone and in which data is not recorded, so that the crosstalk is substantially eliminated. Degradation in the quality of data or disorder in tracking can therefore be prevented, and the more reliable data recording is achieved.
At least one of said physical data in each zone may be a test track used for adjustment of recording power. With this arrangement, the recording power can be adjusted for each zone, and the reliability of the recording can be further improved.
Defect management may be effected for each zone. With this arrangement, even where a defective track is found, it can be substituted for by a track within the same zone, and it is not necessary to switch the clock frequency while accessing the substitute track. As a result, address management for controlling the hardware depending on the actual physical location (where the read/write head is accessing), e.g., for switching the clock frequency, and defect management can be achieved in common, so that the address management is achieved with a high speed.
Each logical track may be composed of 2n sectors, with n being an integer. With this arrangement, the addresses of the sectors are represented by consecutive integers, i.e. they are one-dimensional, so that the calculation of the addresses of the sectors is easy.
An address of each sector may be written 2m times, and an ID may be added to the address at each occurrence to indicate the order of the occurrence. With this arrangement, the addresses each formed of the track address, the sector address and the ID, are linear, or are represented by consecutive integers. Accordingly, the formatter used for formatting such a disk can be formed of a counter. Moreover, the sector addresses can be determined by counting up 2m times. The configuration of the formatter is therefore simple.
An address for each sector may comprise a track address and a sector address, or a track address, a sector address and an ID, which are arranged in the stated order from the side of the MSB. The linear address is incremented by one with increase of the sector number. The formatter is therefore formed of a simple up-counter.
A predetermined number of bits from the heads of true address for each sector represents a virtual logical track. Since the virtual track address is always the predetermined number of bits, the compatibility with the convention optical disk drive devices is improved. For instance, according to the conventional optical disk standard, the PEP region (phase encoding part where the physical properties of the disk or the conditions under which the writing is to be performed are written) has a region for track addresses of only 16 bits. To be compatible with such a standard, 16 bits from the MSB are taken as the virtual track address.
It may be so arranged that an attribute, which is either an attribute indicating a rewritable area, a write-once area or a read-only area, can be independently set for each zone. It is then possible to place different types of areas in a single disk, in various combinations, and disk which best suits to the intended applications can be obtained.
A difference obtained by subtracting the number of parity tracks of each zone from the number of parity tracks of another zone adjacent to and outside of said each zone is preferably constant. Then, it is possible to determine the number of the parity tracks in each zone without referring to a table.
Where a rewritable area and a write-once area are both provided in a single disk, it is preferable that a rewritable area is provided outside of a write-once area. This improves the overall performance of the disk. This is because the rewritable area is more frequently accessed than the write-once area, and the data transfer is rate is higher in the more outward zones.
According to another aspect of the invention, there is provided an optical disk drive device for use in combination with an optical disk comprising a recording region, physical tracks in said recording region each corresponding to one revolution, said recording region being divided into a plurality of zones by one or more circular boundary lines centered on the center of the disk, each zone comprising a plurality of tracks adjacent to each other, wherein an integer number of sectors are provided in each physical track, the angular recording density is higher in the more outward zones such that the linear recording density is substantially constant throughout the recording region, and logical tracks are formed of a predetermined number of sectors. Independent of the physical tracks, said optical disk drive device determining the logical track address and the sector address responsive to a linear logical address by determining the integral quotient and the remainder by dividing the linear logical by the number of the sectors per logical track.
With the above arrangement, conversion from the linear logical address supplied from the host device into the logical track and sector addresses can be achieved through simple calculation on integers and without referring to a table, so that the configuration of the drive device of the software for implementing the conversion may be simple.
According to another aspect of the invention, there is provided an optical disk drive device for use in combination with an optical disk comprising a recording region, physical tracks in said recording region each corresponding to one revolution, said recording region being divided into a plurality of zones by one or more circular boundary lines centered on the center of the disk, each zone comprising a plurality of tracks adjacent to each other, wherein an integer number of sectors are provided in each physical track, the angular recording density is higher in the more outward zones such that the linear recording density is substantially constant throughout the recording region, and logical tracks are formed of a predetermined number of sectors, independent of the physical tracks, wherein a difference obtained by subtracting the number of the logical tracks corresponding to each zone from the number of the logical tracks corresponding another zone adjacent to and radially outside of said each zone is of a constant value, said optical disk drive device determining the zone containing the target sector on the basis of a product of said constant value and the number of the zones.
With the above arrangement, the zone can be determined through simple calculation on integers and without referring to a table, so that the configuration of the device or the software for implementing the determination of the zone may be simple.
According to another aspect of the invention, there is provided an optical disk drive device for use in combination with an optical disk comprising a recording region, physical tracks in said recording region each corresponding to one revolution, said recording region being divided into a plurality of zones by one or more circular boundary lines centered on the center of the disk, each zone comprising a plurality of tracks adjacent to each other, wherein an integer number of sectors are provided in each physical track, the angular recording density is higher in the more outward zones such that the linear recording density is substantially constant throughout the recording region, and logical tracks are formed of a predetermined number of sectors, independent of the physical tracks, said optical disk further comprising a table for recording attributes of the respective zones, said attributes indicating whether each zone is designated as a rewritable area, a write-once area or a read-only area, said table being formed in at least one track or in at least one sector, said optical disk device comprising a means for altering the attributes of the respective zones.
With the above arrangement, it is possible to alter the rewritable are to a write-once area. Such function is desired where the disk or part of the disk is used for storing data that should not be altered without specific permission. It is also possible to alter write-once area to a rewritable area.
According to another aspect of the invention, there is provided an optical disk drive device for use in combination with an optical disk comprising a recording region, physical tracks in said recording region each corresponding to one revolution, said recording region being divided into a plurality of zones by one or more circular boundary lines centered on the center of the disk, each zone comprising a plurality of tracks adjacent to each other, wherein an integer number of sectors are provided in each physical track, the angular recording density is higher in the more outward zones such that the linear recording density is substantially constant throughout the recording region, and logical tracks are formed of a predetermined number of sectors, independent of the physical tracks, said optical disk comprising a first part of the recording region designated as a rewritable area and a second part of the recording region designated as a write-once area, said optical disk device comprising a means for permitting access of only said rewritable area to a host device, and means for altering an attribute of said second part from the write-once area to the rewritable area and copying the data in said first part to said second part while said host device is not accessing the optical disk.
With the above arrangement, the host device needs only to provided a single command, e.g., a back-up command. Then, the drive device executes the back-up command by copying the data from one part of the disk to another. In the execution of the command, the attributes of the zones may be altered before and after copying the data. Moreover, the back-up is achieved within a single disk, so that it is not necessary to back-up the data using another disk.
The optical disk drive device may further comprise means for copying the data in the second part to said first part while said host device is not accessing the optical disk. The host device needs only to provide a single command, e.g., a restore command. Then, the drive device executes the restore command by copying back the data from a write once area to a rewritable area.
The optical disk may have recording regions on first and second surfaces opposite to each other. In such a case, it may be desired if the rewritable area is formed on one of the surfaces and the write-once area is formed on the other surface. Then, even when the data on one of the surfaces is destroyed, identical data can be read from the other surface.